“Hands down the loftiest 15°F bag I’ve ever used,” declared our tester after using the Xenon on a September hike in Colorado’s Flat Tops Wilderness, where her companion grumbled, “It practically fills the tent.” Credit the 850-fill goose down—and lots of it: Marmot crams 20 to 25 percent more down into this women’s model than a comparably rated men’s bag (because many women sleep colder than guys). Much of that extra insulation gets loaded into horizontal baffles at the core and foot, which helps this bag deliver on its 15°F promise: On a 20°F night camped on alpine tundra, our tester never even felt the chill. The comfort-cut mummy is wide through the shoulders and hips (our curviest testers called it “efficient but unrestrictive”), yet tapers sharply at the foot to reduce dead air space around cold-prone toes.

The Shocking Blue is a completely new approach to sleeping bag design incorporating an anatomical cut in every baffle including the hood. At the foot end of the bag the base compartments have been raised and angled to follow the natural flex of the foot keeping your feet surrouded by our fully lofted high quality French down. The Marie Antoinette inner collar prevents body heat escaping from the core section of the bag. Outer and inner fabric is our Asahi Kasei Anti Static Impact 66 Polyamid rip stop imported from Japan. Meticulous attention to the anatomy of the human form while designing each chamber of this bag creates an unprecedented fit. Best use: Backpaking and outdoor adventures late into the year when the temperatures are starting to fall.